Field of the Invention
The present invention relates to an aqueous solution containing an N-long chain acyl acidic amino acid (specifically an N—C8-22 acyl acidic amino acid) and/or a salt thereof, and a production method thereof.
Discussion of the Background
Since N-long chain acyl acidic amino acid salt has a surface active action, a sterilizing action, a metal corrosion suppressive action and the like, it is useful as a starting material of detergents, dispersing agents, emulsifiers, antibacterial agents, preservatives and the like. Particularly, it is highly useful as a starting material of detergents such as shampoo, body shampoo and the like since it is mild to the skin.
As a method of synthesizing N-long chain acyl acidic amino acid (e.g., N-long chain acylglutamic acid) or a salt thereof, a method including condensing acidic amino acid (e.g., glutamic acid) or a salt thereof and long chain fatty acid chloride in a water solvent, or a mixed solvent of hydrophilic organic solvent such as acetone, t-butanol, propylene glycol and the like and water, in the presence of a base is known (Schotten-Baumann reaction, see, for example, patent document 1). In patent document 1, however, the obtained N-long chain acyl acidic amino acid is precipitated to recover same as a solid, and the utility of the aqueous solution per se after the reaction has not been evaluated.
In addition, N-long chain acyl acidic amino acid dipeptide is known as a substance that improves water resistance and creaky feeling of detergents containing N-long chain acyl acidic amino acid (patent document 2). However, N-long chain acyl acidic amino acid dipeptide needs to be obtained by acylating acidic amino acid dipeptide by the Schotten-Baumann reaction and the like, and is an expensive substance difficult to obtain.